The Sinking Skyline
Cities are pumping out the water beneath them, and the ground is settling into the gap. In many coastal cities the land is now dropping faster than the sea is rising.
That's how fast parts of Mexico City sank between Oct 2025 and Jan 2026, according to early radar data from NASA–ISRO's NISAR satellite. Annualized, that is about 40× the 2024 rate of global sea-level rise (0.59 cm/yr).
From a few millimetres to a foot a year
Measured sinking rates, on a log scale. The blue tick is how fast the ocean rose in 2024. Everything to its right is land dropping faster than the sea is climbing.
Log scale, mm per year. Mexico City NISAR value annualized from ">2 cm/month" (Oct 2025–Jan 2026, preliminary). Ranges compress different years and methods, so read it as orders of magnitude.
Where the ground is going
Satellite radar (InSAR) now tracks ground motion to the millimetre. The fastest sinking clusters on soft river deltas and old lakebeds sitting on top of heavily pumped aquifers.
Schematic map. Dot area scales with peak reported sinking rate.
- Mexico City (2007–11)>300 mm/yr
- North Jakarta, peak areasup to 250
- Tianjin · Karachi · Manilaup to ~50
- Houston, fastest 12% of city>10
- 28 largest US cities2–10
- Global sea level, 20245.9
The land is outrunning the ocean
Peak sinking rates in places with heavy pumping, compared with how fast the global sea rose in a record year.
Linear scale, mm per year. San Joaquin figure = ~9 m ÷ 52 years (our calculation). Peak or localized rates, not city-wide averages.
Nine metres in fifty-two years
Near Mendota, California, a USGS pole marks where the San Joaquin Valley floor used to be. Farm wells drew down the aquifer and the land dropped about 9 metres between 1925 and 1977.
Only the 1925 and 1977 endpoints are plotted from USGS. The line between them is a straight interpolation. The blue line is illustrative: 5.9 mm/yr held for 52 years ≈ +0.31 m.
It can be stopped
Tokyo's lowland was sinking up to ~24 cm a year in 1968. Japan and Tokyo capped well pumping through the 1960s and early '70s. By 1975, withdrawals in the region had dropped to about a tenth of their peak.
Subsidence had largely ceased by the mid-1970s, once groundwater levels began to recover. Compacted clay does not spring back, so the lost height is permanent, but the sinking itself stopped.
Who stands on sinking ground
Subsidence quietly multiplies flood risk. It cracks pipes, tilts buildings and lowers levees. It also steals the height that coastal defences were designed around.
Ao et al. also project that 22–26% of China's coastal land could sit below sea level by 2120 once subsidence and sea-level rise are combined (modeled).
What you can do
Sea-level rise is global and slow to steer. Subsidence is local and largely human-made, so it is one of the few coastal threats a city can actually switch off.
Know your ground
Free InSAR ground-motion maps now exist for many regions, for example Europe's Copernicus EGMS. Check whether your neighbourhood is moving before you buy or build.
Back aquifer rules
Metering, pumping caps and switching to surface water worked in Tokyo. Local water boards decide these rules, and public comment counts.
Count sinking in flood plans
Ask that local flood maps use relative sea level, meaning ocean rise plus land drop. In many deltas the land drop is the larger number.